DESCRIPTION: The objectives of this project are to understand the[unreadable] regulation and the in-vivo function of monoamine oxidase (MAO) A and B,[unreadable] which are isoenzymes important for the degradation of monoamine[unreadable] neurotransmitters and biogenic amines. Abnormal levels of MAO activity have[unreadable] been associated with a number of mental disorders. A better understanding[unreadable] of these isoenzymes will allow for the development of more effective[unreadable] treatments for mental disorders. The specific aims are outlined below:[unreadable] [unreadable] To study the function of both MAO A and B in neurotransmitter metabolism and[unreadable] behavior using double knock-out (KO) mice MAO A and B (A/B) double KO mice[unreadable] will be generated by inactivating the MAO A gene of MAO KO mice via[unreadable] homologous recombination. PCR, Southern blot analysis, MAO catalytic[unreadable] activity and Western blot analysis will be used to ensure that both MAO A[unreadable] and B are deficient in these mice. Brain levels (whole brain and regions)[unreadable] of serotonin, norepinephrine and dopamine (MAO A substrates) and their[unreadable] metabolites will be determined in MAO A/B double KO and wild type mice by[unreadable] high pressure liquid chromatography (HPLC). Brain levels of the[unreadable] neuromodulator B-phenylethylamine (MAO B substrate) will be determined by[unreadable] Gas Chromatography/Mass Spectrometry (GC-MS). These levels will be[unreadable] correlated with MAO A and B catalytic activity. Aggressive behavior will be[unreadable] analyzed in male MAO A/B double KO mice and correlated with brain[unreadable] neurotransmitter levels.[unreadable] [unreadable] II. To investigate the role of factors F, M and Sp1 in the regulation of[unreadable] MAO B gene expression. The essential DNA bases required for factors F and M[unreadable] binding will be determined by site-directed mutagenesis and the role of each[unreadable] factor in MAO B gene expression will be identified by gel retardation and[unreadable] promoter activity assays. Using UV crosslinking experiments we will[unreadable] determine if the factors comprise of a single or multiple polypeptides.[unreadable] Full-length cDNAs encoding factors F and M will be cloned and their[unreadable] functional validity will be determined by gel retardation assays with[unreadable] expressed proteins. The cDNA encoding factor F, M and Sp1 will be[unreadable] transfected and the effect of expressed factors on MAO B expression in vivo[unreadable] will be studied by determination of promoter activity, MAO B mRNA levels,[unreadable] protein levels and catalytic activity.[unreadable] [unreadable] These studies are important for both basic neuropharmacology and clinical[unreadable] research.